Temperature control system for ovens heated by hydrocarbon burners



May 17, 1938. E. HILLEBRAND 2,117,556

'TEMPERATURE CONTROL SYSTEM FOR OVENS HEATED BY HYDHGCARBON BURNERS Original Filed March 1935 Cil Patented May 17, 1938 PATENT OFFICE TEMPERATURE CONTROL SYSTEM FOB OVENS HEATED BY nUnNnns HYDROCARBON Earl Hillebrand, Albert Lea, Minn., assignor to American Gas Machine Company, Inc., Albert Lea, Minn., a. corporation of Delaware Application 5 Claims.

March 20, 1935, Serial No. 11,992 Renewed May 24, 1937 This invention relates to ovens wherein the a mixing chamber X. Mixing chamber X has heating medium is supplied by means of a hydrocarbon burner and more particularly to a system for generating and feeding the mixed fuel to the oven burner in such manner that the temperature within the oven may be maintained at various desired temperatures Within a given range.

It is an object of my invention to provide a system adapted for association with conventional types of hydrocarbon generators whereby the amount of mixed fuel admitted to the oven burner is controlled by heat responsive mechanism dependent upon the temperature within an oven.

It is a further object to provide a system and apparatus of the class above referred to wherein the apparatus may be adjusted to maintain various predetermined temperatures within theV oven within a relatively wide range.

More specifically it is an object to provide such a system wherein a main generating tube and an auxiliaryor pilot generating tube are both subjected to heat from a generating burner and 'wherein mechanism controlled by the temperature within the oven is supplied for cutting in or out the supply of liquid fuel to the main generating tube in order to vary the amount of mixed fuel admitted to the oven burner as required to maintain the oven temperature at the desired predetermined point.

These and other objects and advantages of the invention will be more fully set forth in the following description made in connection with the accompanying drawing, in which like reference characters refer to similar parts throughout the several views, and in which:-

Fig. 1 is a more or less diagrammatical perspective view showing an embodiment of my invention and operatively associated with a suitable hydrocarbon generator and with an oven and oven burner, and

Fig. 2 is a vertical section taken longitudinally through a suitable form of heat responsive fuel control mechanism utilized in my system.

As shown in the drawing, my improved oven temperature control system and fuel feedingsystem. is associated with a hydrocarbon generator which may be of any suitable type.` 'I'he generator illustrated is of the general type disclosed in the co-pending application of Hans C. Hanson and Walter Olsen, S. N. 694,082, led October 18, 1933, and a detailed description thereof is thought lmnecessary. The generator includes a generating burner B connected with a manifold M, which manifold receives the combustible mixture from a conduit C communicating at its upper end with extending therein the delivery end or ends of fuel generating means and is further provided with an air intake opening, not shown.

A portion of the wall O defining an oven is shown in Fig. 1 and an oven burner OB is mounted in the lower part of the oven connected by a conduit 3 with the fuel mixing manifold M.

Valve mechanism Y for controlling ow of fuel and air to the burner for starting purposes is associated with the generator but has no cooperative relationship with the apparatus of my present invention.

In my control system I prefer to utilize a pair Y of generating tubes 4 and 5, both of which communicate at their rear ends with the interior of mixing chamber X terminating in very small nozzles having injector elect, which are disposed inwardly of the front wall of chamber X. The main generator tube 4 has greater capacity and a nozzle orifice of substantially greater size than the auxiliary or pilot generator tube 5, the discharge orifice of which is restricted so that it may only discharge a very small spray of fuel. Shut 01T valves 6 and 'I of conventional type are provided for generator `tubes 4 and 5 respectively. The liquid fuel line 8 from the supply tank connects with a branch fitting 9, one leg of which is connected by a. pipe l0 with the auxiliary or pilot generator 5. The other leg or branch of tting 9 is connected with the intake passage llcV of a temperature responsive feed controlling mechanism indicated as an entirety by the letter T. Said mechanism includes a valve body I I mounted in a suitable casing I2 as shown of cylindrical form and having connection nipples which form or assist in forming the intake passage Ila and outlet passage IIb, said nipples being horizontally aligned and extending through a slot |2a formed in the top of casing I2 to permit slight relative longitudinal movement of valve body H Within casing I 2 as will later more fully appear. 'The outlet nipple and passage IIb is connected by pipe I3 with the forward end of main generator tube l. Within valve body i I and extending axially thereof is a relatively large communicating passage llc forming a valve chamber with one end of which intake passage Ila communicates and with the other end of which the outlet passage I Ib communicates, it being noted that as shown outlet passage IIb communicates with passage llc axially thereof to provide an axially disposed valve seatwith which a plug type valve 'I4 is adapted to cooperate. Valve Il has an enlarged head which slidably lits within the cylindrical walls of chamber llc and is urged away from its seat by means of a coiled compression spring l5 surrounding the body of the valve. It will be obvious that when valve i4 is in open position as shown in Fig. 2, liquid fuel will pass through inlet passage lla through the communicating passage or chamber l lc and out of the valve body through outlet passage IIb and then through pipe i3 into the main generating tube d. The head of valve it abuts against an air-tight diaphragm i6 mounted behind the valve and the nexing of said diaphragm and longitudinal movement of valve M is effected by means of an abutment plug l'l slidably mounted ina cup i8 which is fixed to the movable end of an expansible member or, bellows I8 of the sylphon type. Cup lll is slidably mounted in a plug fitting 20 which as shown is screwed axially into the rear end of valve body il and which also acts to retain diaphragm it in operative position. Compression spring l8a is interposed between abutment 'plug lll and cup lli to yleldingly hold the abutment plug in extended position. Bellows I9 is connected by a small conduit 2l with a closed tube 22 mounted. in the upper portion of the oven O, and tube 22, conduit 2l and bellows i8 are lled with a heat expansive uid. The closed tube 22 is preferably constructed of heat conductive material, such as copper, or silver. l

The compression spring 98a takes up any excess movement of abutment plug i8 due to continued expansion of the bellows i9 after valve Il has been closed. Spring l5, of course, is adapted to unseat the valve when bellows l@ contracts beyond a predetermined point.

To adjust the setting of my apparatus for various predetermined temperatures within oven O, I provide an adjustment screw 23 having threaded engagement with a heavy plug 26 at the forward end of cylindrical casing l2'and the inner end of which abuts against the forward end of valve body ll and therefore effects longitudinal movement of the valve body relatively to the valve Il mounted therein. The outer end of vadjustment screw 23 is provided with a manipuat which time the oven O is cool and valve il is then removed from its seat in communication with passage lib. Liquid fuel from the source of supply then passes through the line 8 into the valve body through inlet passage lla through communicating passage or chamber llc andv out of the valve body through outlet passage lib and into the main generating tube through conduit il. Oven burner OB may be supplied with combustible fuel by opening valve V and may be lighted. Until the oven reaches a predetermined temperature, liquid fuel. will continue to pass through the valve body of the temperature responsive mechanism and into the main generating tube. Some small amount of fuel may also pass through the auxiliary or pilot generator tube 5, but because of the small orifice of the same. most of the fuel or combustive mixture will pass through the main generator until valve Il is.

closed.

The expansion of iiuid in the closed tube 22 within the oven in turn expands bellows I9,mov

by longitu.- i `y moving the valve to closed position and cutting oif the ow of liquid fuel to the main generating tube. .All fuel supplied to mixing chamber X then` must be discharged bythe oridce of pilot or auxiliary vaporizing tube t and of course the amount of fuel consumed will be relatively wy v until the temperature of the oven again c for additional heating medium to maintain the desired predetermined temperature.

From the foregoing description it will be apparent that I have provided a simple, comparatively economical and highly eicient system for maintaining the ovens of hydrocarbon stoves and the like at various predetermined temperatures. It will further be understood that while in the drawing I have illustrated mechanism which supplies only combustible fuel for an oven burner and a generator burner, that numerous other burners may be connected with manifold M as desired.

It will, of course, be understood that various changes may be made in the form, details, proportions and arrangement of the parts, without departing from the scope of my invention, which generally stated, consists in a device capable of carrying out the objects above set forth, and in the novel parts and combinations of parts disclosed and dened in the appended claims.

What is claimed is:-

l. A heating and temperature control system Afor an oven, having in combination; a hydrocarbon fuel generator comprising a burner, a mixing chamber, and fuel vaporizing means subjected to the heat from said burner and being connected with a source of liquid fuel supply, said means having a pair of discharge elements communieating with said mixing chamber, mechanism for cutting olf supply of fuel to one of said elements and means responsive to the temperature of said oven for operating said mechanism to maintain said oven at a substantially predetermined temperature.

2. A heating and temperature control system for an oven, having in combination; a hydrocarbon fuel generator comprising a burner, a mixing chamber, and fuel vaporizing means subjected to the heat from said burner and being connected with a source of liquid fuel supply, said vaporizing means having a pair of discharge elements communicating with said mixing chamber, one being adapted to discharge vaporlzed fuel at a considerably greater rate of discharge than the other, mechanism for cutting oil.' supply of fuel to said larger capacity element and means responsive to the temperature of said oven for operating said mechanism to maintain said oven at a substantially predetermined temperature.

3. A heating and temperature control system for an oven having in combination; a hydrocarbon fuel generator comprising a burner. a mixing chamber, a pair of fuel vaporizing tubes both subjected to the heat from said burner and both adapted to discharge vaporized fuel into said mixing chamber, means connecting one of said tubes at all times with a source of liquid fuel and means adapted to connect said other tube with said source of liquid fuel, mechanism for connecting and disconnecting said second mentioned tube with said source; an oven having a burner therein connected with the mixing chamber of said generator; and means responsive to the temperature of said oven for operating said mechanism to maintain said oven at a substantially predetermined temperature.

4. A temperature control system for an oven having in combination, a hydrocarbon fuel generator comprising a burner, a main generating tube and an auxiliary generating tube, both of said tubes being mounted in position to be heated by said burner, a mixing chamber having an air entrance and having communication vwith the delivery ends of both of said generating tubes, a burner for heatingsaid oven connected with said air mixing chamber, a liquid fuel line having a connection with said auxiliary generator, a valve body having a passage therein, one portion of which is connected with said fuel line and another portion of which is connected with said main generator tube, a valve mounted in said body between said connections adapted to close communication between said. passage and the connection with said main generator tube and temperature responsive means disposed in said chamber and adapted to control the operation of said valve.

5. A heating and temperature control system for an oven, having in combination; a hydrocar-V bon fuel generator comprising a burner, a mixing chamber, and fuel vaporizing means subjected to the heat from said burner, said vaporizing means comprising a pair of vaporizing elements, both of which deliver to said mixing chamber,

connections between said elements and a source EARL mLmBRAND. 2o 

